<!DOCTYPE html>
<html>
<head>
	<title></title>
</head>
<body>
	<canvas id="canvas" width="500" height="500" style="border: 1px solid #ccc"></canvas>

</body>
</html>

<script type="text/javascript">
	var canvas = document.getElementById('canvas');
	var context = canvas.getContext('2d');
	var gr = context.createRadialGradient(200,200,10,200,200,150);
	gr.addColorStop(0,'red');
	gr.addColorStop(0.3,'green')
	gr.addColorStop(0.6,'yellow')
	gr.addColorStop(1,'white');
	context.fillStyle =gr;
	context.arc(200,200,150,0,Math.PI*2);
	context.fill();

</script>